Window-type ball grid array package structure and fabricating method thereof

Abstract

A window-type ball grid array (WBGA) package structure includes a substrate, fingers, traces, a solder mask, a die, a window mold compound and solder balls. The substrate has a first surface and a second surface and a window passing there-through. The fingers are on the first surface near the window, and each trace is on the first surface and connected to each finger. Moreover, the traces and a part of the fingers connected thereto are covered by the solder mask. The die is on the second surface and covers the window, and the window is filled by the window mold compound extendedly covering a part of a top surface of the solder mask. Additionally, the solder balls are on the first surface. Due to the foregoing structure, the stress near the fingers may be reduced and thus the lifetime of WBGA package structure may be efficiently increased.

1 . A window-type ball grid array (WBGA) package structure, comprising:
 a substrate, having a first surface, a second surface, and a window passing through the first surface and the second surface;   a plurality of fingers, formed on the first surface near the window;   a plurality of traces, formed on the first surface and electrically and respectively connected to a corresponding one of the fingers;   a solder mask, covering the traces and a part of the fingers connected to the traces;   a die, securely attached to the second surface and covering the window;   a window mold compound, filling the window and extendedly covering a part of a top surface of the solder mask; and   a plurality of solder balls, disposed on the first surface.   
   
   
       2 . The WBGA package structure as claimed in  claim 1 , wherein each finger comprises:
 a copper layer; and   a Ni/Au layer, located on the copper layer surface without being covered by the solder mask.   
   
   
       3 . The WBGA package structure as claimed in  claim 1 , wherein a width (W f ) of each finger is over 1.5 times larger than a line width (W t ) of each trace. 
   
   
       4 . The WBGA package structure as claimed in  claim 3 , wherein the die further comprises a pad located on a surface facing the window. 
   
   
       5 . The WBGA package structure as claimed in  claim 1 , wherein the trace is made of copper. 
   
   
       6 . The VVBGA package structure as claimed in  claim 4 , wherein the solder balls are electrically connected to the fingers by the traces. 
   
   
       7 . The WBGA package structure as claimed in  claim 1 , wherein the solder balls are made of copper, tin, lead, or any alloy thereof. 
   
   
       8 . The WBGA package structure as claimed in  claim 3 , further comprising an adhesion layer located between the die and the substrate.